Expert Opinions

Should diesel cars be banned from cities?

Chair of the Executive Bodyof the UNECE Convention onLong Range Transboundary Air Pollution

Diesel cars have been regarded as the “green” option when choosing a car, chiefly because they’re supposed to offer better fuel consumption and lower carbon dioxide emissions.

Recently, however, their image has begun to change as data become available about their emissions of harmful air pollutants. Diesel vehicles emit more harmful particulate pollution, and these particles can not only be harmful as a total mass of coarse or fine particulate matter, but they also contain harmful carcinogens such as polycyclic aromatic hydrocarbons.

Emission regulations have been ineffective for diesel cars. Levels of nitrogen oxide emissions, for instance, haven’t fallen significantly over the past 20 years. These emissions are not only harmful in themselves but also precursors of acid rain and ozone.

In June 2012 the International Agency for Research on Cancer classified diesel exhaust in Group 1 in its ranking scheme, meaning carcinogenic to humans. There are now regulations to reduce particle emissions from newer diesel cars entering the fleet, and future regulations are intended to reduce nitrogen oxide emissions. However, given past experience it would be prudent to maintain some scepticism on the performance of new diesel cars and to recognize that there are still a very large number of older, more polluting vehicles in the European car fleet. Ban the more polluting cars from city centres? Possibly not, but measures to discourage their use through “low emission zones” or fiscal measures would seem to be a promising avenue for regulators.

Opinions expressed in this section are those of the author(s) and do not necessarily reflect the official position of UNECE, of the bodies established under its international legal agreements/conventions, or of the secretariat.